Ecology applies the scientific method to the natural world. It relies on chemistry and biology extensively to describe the parts found in the living bodies in that world, but tries to avoid assumptions about how they behave.
Greens treat ecology as the basis of a system of natural law - that is, human beings are obligated not to try to set up systems that really compete with ecology or challenge ecosystem health, because this is either a bad political choice, a bad moral choice (this view is probably scientism) or it has negative consequences for human health. The Green Parties put ecological wisdom first on a list of six principles.
Urban ecology and industrial ecology study human built systems that do not compete with nature, but in some ways alter people's mutual cognition and help to remove them from it.
See w:ecology and w:list of ecology topics.
See also ecology in Simple English.